Indian Journal of Dental ResearchIndian Journal of Dental ResearchIndian Journal of Dental Research
HOME | ABOUT US | EDITORIAL BOARD | AHEAD OF PRINT | CURRENT ISSUE | ARCHIVES | INSTRUCTIONS | SUBSCRIBE | ADVERTISE | CONTACT
Indian Journal of Dental Research   Login   |  Users online: 160

Home Bookmark this page Print this page Email this page Small font sizeDefault font size Increase font size         

 


 
Table of Contents   
ORIGINAL RESEARCH  
Year : 2011  |  Volume : 22  |  Issue : 4  |  Page : 542-546
Morphometrical and morphological study of mental foramen in dry dentulous mandibles of South Andhra population of India


Faculty of Medicine, Department of Anatomy, Narayana Medical College, Chinthareddypalem, Nellore, Andhra Pradesh, India

Click here for correspondence address and email

Date of Submission04-Jan-2010
Date of Decision27-Apr-2010
Date of Acceptance16-Nov-2010
Date of Web Publication26-Nov-2011
 

   Abstract 

Background: Mental foramen (MF) is an anatomical structure of particular importance in local anesthesia and surgical procedures in terms of achieving effective mandibular nerve blocks and avoiding injuries to the neurovascular bundles.
Aim: To determine the morphometry and morphology of MF in south Andhra population of India, hitherto unreported.
Materials and Methods: Ninety dry dentulous mandibles of both sexes were examined for position, size, shape and number of MF.
Results: Various parameters investigated are, the horizontal distance between (1) symphysis menti and MF was 27.2 mm on right and 27.7 mm on the left, (2) MF and posterior border of ramus was 70.7 mm on both sides, vertical distance between (3) MF and inferior border of mandible was16.5 mm on right and 14.3 mm on left, (4) alveolar crest and MF was 13.7 mm on right and 16.4 on left, (5) distance between the MF and below the apex of premolar socket was +2.8 mm on right and +3.5 mm on left and above the socket was -2.8 mm on right and -2.7 mm on left. Occurrence of MF below the second premolar tooth was found to be highest (73.2%). Average size of MF was larger on left and its way of exit was in postero-superior direction. Shape of MF was round in 79% and oval in 21% and double MF was found in 8.9% of mandibles.
Conclusions: In the present study, most common position of MF was found below the apex of second premolar in 73.2% and between the second premolar and first molar in 19% of mandibles. The other morphometrical findings of this study may be implicated by dental practitioners and maxillofacial surgeons

Keywords: Mental foramen, morphometry, mental anesthesia, apicocurretage of mandibular premolar, location of mental foramen

How to cite this article:
Sankar DK, Bhanu SP, Susan P J. Morphometrical and morphological study of mental foramen in dry dentulous mandibles of South Andhra population of India. Indian J Dent Res 2011;22:542-6

How to cite this URL:
Sankar DK, Bhanu SP, Susan P J. Morphometrical and morphological study of mental foramen in dry dentulous mandibles of South Andhra population of India. Indian J Dent Res [serial online] 2011 [cited 2019 Sep 15];22:542-6. Available from: http://www.ijdr.in/text.asp?2011/22/4/542/90290
Mental foramen (MF) is situated in anterolateral aspect of the body of the mandible which transmits mental nerve, artery and vein. Sensation from the skin of chin, lower lip and the labial mucosa is carried by mental nerve, a branch of the inferior alveolar nerve. [1] MF serves as an important anatomical land mark, the orientation and position of which facilitate surgical, local anesthetic and other invasive procedures for oral and maxillofacial surgeries. Understanding the anatomy of this region is essential for performing effective nerve blocks, and avoiding injuries to the neurovascular bundles. Identification of accurate anatomical position of MF is very important in periodontal surgery, flap operation of lower teeth, apicocurretage of mandibular premolars, retrograde amalgam filling, surgical orthodontics and other lower lip surgical procedures. For example, in apicocurretage of mandibular premolars, the dentist depends on the relation of the MF to the lower premolar and to the body of ramus, otherwise operation on the lower premolar may damage the mental nerve. The mental nerve injury can cause transitory or permanent sensitive, thermal and tactile changes in the areas of its innervations. [2],[3],[4]

The position of the MF has been studied by means of direct measurement on dry mandibles or by using radiographs of dry mandibles or patients. [5],[6],[7] Standard anatomical [1] and radiological textbooks [8] contain conflicting statements regarding the location of MF. Schaeffer [9] stated that the MF was located between the spaces of mandibular premolars. The position of MF may be present between the apex of lower premolars or below the apex of second premolar. [6],[10],[11] According to Tebo and Telford, [12] location of MF is present below the apex of the second mandibular premolar which was similar to the findings of Suresh et al. [13] Numerous data on the position of MF varies in different ethnic groups like British, [10] Chinese, [6] Indian, [14] Saudi Arabian population [15] and racial difference in the position of MF was reported by Green. [16] In view of these discrepancies among the various investigations, it is no surprise that there are repeated failures to locate the MF for injections and other operative surgeries. Knowledge of the most common position of the MF of a local population gives additional information in the mental nerve blocks and related mandibular surgeries.

The present study was undertaken to provide information on anatomical location, size and shape of MF of the South Andhra population of India hither to unreported. The results of this study may furnish a reference for dentists in clinical practices.


   Materials and Methods Top


Ninety dry dentulous adult mandibles, irrespective of their sex belonging to South Andhra population of India comprised the subjects for this study. The mandibles with premortem tooth loss were excluded because the MF comes closer to the alveolar crest margin or sometimes alveolar area itself due to alveolar bone resorption. Before measuring, mandibles were placed on a standard horizontal plane to which the lower border of the mandible get its most contact when vertical pressure is applied to the molars. [10],[11],[17],[18]

Various parameters were measured using Vernier caliper, metallic wire and scale on both the right and left sides. The distance between the MF to symphysis menti (SF), posterior border of the ramus (FR), alveolar crest (AF) and base (FB) were taken by a metallic wire parallel to the standard horizontal plane, after which it was measured by using a standard scale. Similarly the distance between apex of the alveolar socket and upper border of the MF was measured from the values of A1 and A2.

  • SF between symphysis menti and most anterior margin of MF [Figure 1]
  • FR between most anterior margin of MF and posterior border of ramus of mandible [Figure 1]
  • FB between inferior margin of MF and inferior border of mandible perpendicular to horizontal plane [Figure 2]
  • AF between the alveolar crest and inferior margin of MF, perpendicular to horizontal plane [Figure 2]
  • A1 is the distance between alveolar crest to upper most point of MF [Figure 3] and
  • A2 is the distance between the alveolar margins to the apex of second premolar socket [Figure 3].


In addition, size, shape, multiple foramina and direction of exit were also noted. The average size of the foramen was measured with the help of vernier caliper by measuring its maximum length and breadth. The mean values are expressed as mean±SD with 95% confidence intervals. Mean values on left and right sides were compared applying Student's 't' test using SPSS 12.0 statistical software. Proportions were compared using Pearson's χ2 test.
Figure 1: Location of mental foramen in relation to symphysis menti (SF) and posterior border of ramus (FR)

Click here to view
Figure 2: Location of mental foramen in relation to inferior border of mandible (FB) and alveolar crest (AF)

Click here to view
Figure 3: Relative difference between apex of lower second premolar socket and upper most point of mental foramen (A1-A2)

Click here to view



   Results Top


In relation to mandibular tooth, the position of the MF was below the apex of the second premolar teeth in 66 mandibles (73.2%). In seven mandibles (7.8%), it was found between second premolar and first molar and in 17 mandibles (19%) it was below the apex of the first molar teeth [Figure 4]. Relative position of MF was found to be along the long axis of a teeth or interdental space [Figure 4].
Figure 4: Position of MF in relation to mandibular molar and premolars

Click here to view


The distance between the MF and symphysis menti was 27.2±2.4 mm on right side (Right SF) and 27.7±2.4 mm on left side (Left SF) and the distance between the MF and posterior border of ramus was 70.7±4.2 mm on right side (Right FR) and 70.7±4.2 mm on left side (Left FR) [Table 1].
Table 1: Morphometrical parameters of mental foramen and values are expressed in millimetres

Click here to view


The results of the measurement between the MF and alveolar crest was 13.7±2.8 mm on right side (Right AF) and 16.4±2.9 mm on left side (Left AF) and between the MF and inferior border of body of mandible was 16.5±2.1 mm and 14.3±2.1 mm on right (Right FB) and left (Left FB) sides, respectively [Table 1].

The distance between apex of lower second premolar socket and upper most point of MF (A1-A2) was +2.813 mm on the right side in 48 mandibles and +3.571 mm on the left sides in 28 mandibles, in which the position of the MF was found below the apex of the second premolar sockets. In 23 mandibles, it was -2.826 mm on right side and in 42 mandibles; it was -2.762 mm on left side, in which the MF was above the apex of the socket [Table 2]. The χ2 value is highly significant and the P value is <0.004
Table 2: Location of mental foramen of right and left side in relation to apex of premolar sockets

Click here to view


The average size of the foramen was found to be larger on left side (3.3 mm) than the right sides (2.8 mm) and its usual way of exit was in a postero-superior direction in both the sides [Table 3].
Table 3: Morphological parameters of the mental foramen

Click here to view


Shape of the MF was visually recognized and analysed in which out of 90 mandibles, in 71 cases (78.9%) it was found to be round or circular shape and in 19 cases (21.1%) it was oval or elliptical. Generally, the margins of the foramen were smooth [Table 3].

Double mental foramina were found in some of the mandibles in addition to the normal MF. In this study, out of 90 mandibles, single MF was found in 82 (91.1%) mandibles and accessory mental foramina was seen in eight (8.9%) mandibles, in which openings were not of equal size [Figure 5].
Figure 5: Mandible showing the double mental foramina (arrow) on right (R) and left (L) side

Click here to view



   Discussion Top


In human being the MF is usually a single opening on each side of the body of the mandible. However, in some cases there may be complete absence of MF or it may be in multiples. [19] Being an important landmark for dental surgical procedures, the location of MF should be known accurately in relation to premolars, molars, symphysis menti, posterior border of ramus, alveolar socket, alveolar crest and mandibular body. The reason for the difference in location could be due to the shape of the foramen itself. As this study was conducted in dry dentulous mandibles, the instances of premortem tooth loss mandibles were excluded due to the reason for its alveolar resorption which may also alter the position of MF. [20],[21]

In the present study, the common position of MF was below the apex of second premolar teeth with the occurrence of 73.2%. The previous investigations of position of MF was observed to be 68.58% in North Indian population, [13] 58.9% in Chinese population, [6] 52.9% in British mandibles, [10] 55.6% in Nigerians, [22] 45.3% in Saudi population, [15] 47.2% in Iranian population [23] and 56.1% in Kenyan African mandibles [24] [Graph 1].



In relation to apex of mandibular premolar sockets, MF on right side was situated in 53.3% below the level; 25.6% above the level and the remaining 21.2% situated at the level of apex of socket. While on the left side it was situated in 31.1% below the level; 46.7% above the level and the remaining 22.2% at the level of apex of socket.

On the whole in both right and left sides, the distance between the apex of premolar socket and upper most margin of MF (A1-A2) was showing positive values (+) in 76 mandibles i.e., the MF was below the apex of socket and negative values (-) in 65 mandibles in which the MF was above the apex of socket. This indicates that MF in most of the mandibles was situated below the apex of premolar sockets which was similar to the findings of Wang et al. [6] in Chinese mandibles.

The values of difference between A1 and A2 on the left side in this study showed the position of the MF present above the level of the socket in 46.7% of mandibles which coincides with the findings of Suresh et al. [13] in North Indian populations. Owing to this small distance between the apex of tooth socket and MF, there is possibility of damaging the mental nerve or inferior dental nerve during endodontic treatment like root canal filling. [25],[26]

The ratio of distances between symphysis menti to foramen (SF) and foramen to posterior border of ramus (FR) was 1:2.6 in our study, which when compared with North Indian population was 1:1.3, [13] 1:2.6 in Chinese [6] and 1:2.7 in British mandibles. [10] Green RM [16] reported that the location of the MF is more anterior in the Caucasoid group which is similar to our findings.

In relation to the shape of MF, the ratio between oval and circular types of MF was 1:3.7 in this study. It was found to be 1:3 by Suresh et al. [13] in North Indian population and 1:1.9 by Gershchenson et al. [14] which he studied in two-thirds of Israeli and one-third of Indian mandibles.

In the present study double mental foramina were found to be 5.6% on the right and 3.3% on the left side. Triple and more than that were not found in this study. Gershchenson et al. [14] reported 7.51% of double foramina in Indian and Israeli mandibles. Suresh et al. [13] and Zografos and Mutzuri [27] studied the incidence of double foramina in 11.48% of North Indians and 6.68% of Greek population, respectively. However, in 2.17% of North Indian mandibles triple MF was also reported by Suresh et al. [13] A very rare occurrence of absence of MF was reported by de Frietas et al. [7]

Kjaer [28] has found that the prenatal location of the MF is in the alveolar bone between the primary canine and first molar which may be altered due to a lag in prenatal development. The location of the MF may also change with age and loss of teeth due to alveolar bone resorption.

Thus, size, shape, number of foramen and location may vary with population. The present study reports that the MF on an average was found to be below the second premolar which was found to be highest when compared to the findings of other authors. Other parameters showed a slight difference which is not statistically different from previous studies.

As the position of MF is usually difficult to locate, there are no accurate anatomical landmarks for the MF to be identified neither clinically nor can be palpated externally. The knowledge of exact position and various distances of MF are necessary for its anesthetic and surgical intervention. The location and other relative parameter of the MF in South Andhra population of India has not been described previously, for which this study was undertaken to determine the most common location of the MF. The results of the present study add to the information of the MF for the approach of mental nerve and have implications for dental practitioners and maxillo-facial surgeons.


   Acknowledgment Top


We the authors sincerely thank Dr. N. Kannan, MDS, Department of Oral Medicine and Radiology, Narayana Dental College, Nellore, Andhra Pradesh for his valuable suggestions and Dr. E. Venkat Rao, MD, Department of Community Medicine, Narayana Medical College, Nellore, Andhra Pradesh for his assistance in computer aided statistical work.

 
   References Top

1.Williams PL, Banister LH, Collins P, Dyson M, Dussek JE, Ferguson MWJ. Gray's Anatomy, In: Skeletal system. 38 th ed. New York: Churchill Livingstone; 1995. p. 576-8.  Back to cited text no. 1
    
2.Nkenke E, Schultze-Mosgau S, Radespiel-Tröger M, Kloss F, Neukam FW. Morbidity of harvesting of chin grafts: a prospective study. Clin Oral Implants Res 2001;12:495-502.  Back to cited text no. 2
    
3.Raghoebar GM, Louwerse C, Kalk WW, Vissink A. Morbidity of chin bone harvesting. Clin Oral Implants Res 2001;12:503-7.  Back to cited text no. 3
[PUBMED]  [FULLTEXT]  
4.Sbordone L, Menchini-Fabris GB, Toti P, Sbordone C, Califano L, Guidetti F. Clinical survey of neurosensory side-effects of mandibular parasymphyseal bone harvesting. Int J Oral Maxillofac Surg 2009;38:139-45.   Back to cited text no. 4
[PUBMED]  [FULLTEXT]  
5.Luebke RG, Glick DH, Ingle JI. Indications and contraindications for endodontic surgery. Oral Sur 1964;18:97-113.   Back to cited text no. 5
    
6.Wang TM, Shih C, Liu JC, Kuo KJ. A clinical and anatomical study of the location of the mental foramen in adult Chinese mandible. Acta Anat 1986;126:29-33.  Back to cited text no. 6
[PUBMED]    
7.De Freitas V, Madeira MC, Toledo Filho JL, Chagas CF. Absence of the mental foramen in dry human mandibles. Acta Anat 1979;104:353-5.  Back to cited text no. 7
[PUBMED]    
8.Hutchinson ACW. Dental and oral X-ray diagnosis. Livingston: Edinburgh; 1954. p. 29.   Back to cited text no. 8
    
9.Schaeffer JP. Morris's human anatomy. 10th ed. Blakiston: Philadelphia; 1942. p. 106.  Back to cited text no. 9
    
10.Santini A, Land M. A comparison of the position of the mental foramen in Chinese and British mandibles. Acta Anat 1990;137:208-12.  Back to cited text no. 10
[PUBMED]    
11.Yesilyurt H, Aydiniliogllu A, Kavakli A, Ekinci N, Eroglu C, Hacialiogullari M, et al. Local differences in the position of the mental foramen. Folia Morphol 2008;67:32-5.  Back to cited text no. 11
    
12.Tebo HG, Telford IB. Analysis of the variations in position of the mental foramen. Anat Rec 1950;107:61-6.  Back to cited text no. 12
    
13.Singh SK, Gopinathan K, Bhall U, Chhabra S. Variations in the position and number of mental foramen in mandibles of North Indian population. J Anat Soc Ind 1992;41:47-51.  Back to cited text no. 13
    
14.Greshchenson AL, Nathan H, Luchansky E. Mental foramen and mental nerve: Changes with age. Acta Anat 1986;126:21-8.  Back to cited text no. 14
    
15.al Jasser NM, Nwoku AL. Radiographic study of the mental foramen in a selected Saudi population. Dentomaxillofacial Radiol 1998;27:341-3.  Back to cited text no. 15
    
16.Green RM. The position of the mental foramen: a comparison between the southern (Hong Kong) Chinese and other ethnic racial groups. Oral Surg Oral Med Oral Path 1987;63:287-90.  Back to cited text no. 16
[PUBMED]    
17.Morrant GM. A biometric study of the human mandible. Bio metrika 1936;28:84-122.  Back to cited text no. 17
    
18.Amorim MM, Prado FB, Borini CB, Bittar TO, Volpato MC, Groppo FC, et al. The mental foramen position in dentate and edentulous Brazilian's mandible. Int J Morphol 2008;26:981-7.  Back to cited text no. 18
    
19.Balcioglu HA, Kocaelli H. Accessory mental foramen. North Am J Med Sci 2009;1:314-5.   Back to cited text no. 19
  Medknow Journal  
20.Drennan MR. The mental foramen with special reference to its position in the edentulous mandible. South Afr Dent J 1930;4:494-509.  Back to cited text no. 20
    
21.Wical KE, Swoope CC. Studies of residual ridge resorption. In use of panoramic radiographs for evaluation and classification of mandibular resorption. J Prosthet Dent 1974;32:7-12.  Back to cited text no. 21
[PUBMED]    
22.Kekere-Ekun TA. Antero-posterior location of the mental foramen in Nigerians. Afr Dent J 1989;3:2-8.  Back to cited text no. 22
[PUBMED]    
23.Haghanifar S, Rokouei M. Radiographic evaluation of the mental foramen in a selected Iranian population. Indian J Dent Res 2009;20:150-2.  Back to cited text no. 23
[PUBMED]  Medknow Journal  
24.Mwaniki DL, Hassanali J. The position of mandibular and mental foramina in Kenyan African mandibles. East Afr Med J 1992;69:210-3.  Back to cited text no. 24
[PUBMED]    
25.Orlay HC. Overfilling in root canal treatment. Two accidents with N2. Br Dent J 1966;120:376.  Back to cited text no. 25
    
26.Shochat S, Garfunkel A. Neurologic complication arising from overfilling root canal. Oral Surg 1973;35:684-7.  Back to cited text no. 26
[PUBMED]    
27.Zagrafos J, Mutzuri A. Incidence of double mental foramen in a sample of Greek population. Odontostomatology 1989;43:521-3.  Back to cited text no. 27
    
28.Kjaer I. Formation and early prenatal location of the human mental foramen. Scand J Dent Res 1989;97:1-7.  Back to cited text no. 28
[PUBMED]    

Top
Correspondence Address:
Devi K Sankar
Faculty of Medicine, Department of Anatomy, Narayana Medical College, Chinthareddypalem, Nellore, Andhra Pradesh
India
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-9290.90290

Rights and Permissions


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2], [Table 3]

This article has been cited by
1 assessment of position and bilateral symmetry of occurrence of mental foramen in dentate asian population
ketan gada, s. and nagda, s.j.
journal of clinical and diagnostic research. 2014; 8(2): 203-205
[Pubmed]
2 the mandible and its foramen: anatomy, anthropology, embryology and resulting clinical implications
lipski, m. and tomaszewska, i.m. and lipska, w. and lis, g.j. and tomaszewski, k.a.
folia morphologica (poland). 2013; 72(4): 285-292
[Pubmed]
3 The prevalence, length and position of the anterior loop of the inferior alveolar nerve in Chinese, assessed by spiral computed tomography
Xiao Li,Zhu-Kun Jin,Hui Zhao,Kai Yang,Jian-Min Duan,Wei-Jian Wang
Surgical and Radiologic Anatomy. 2013; 35(9): 823
[Pubmed] | [DOI]
4 Number of accessory or nutrient canals in the human mandible
Johan K. M. Aps
Clinical Oral Investigations. 2013;
[Pubmed] | [DOI]
5 Position of the mental foramen in a Moroccan population: A radiographic study
Ahmed Chkoura,Wafaa El Wady
Imaging Science in Dentistry. 2013; 43(2): 71
[Pubmed] | [DOI]



 

Top
 
 
 
  Search
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Email Alert *
    Add to My List *
* Registration required (free)  
 


    Abstract
    Materials and Me...
   Results
   Discussion
   Acknowledgment
    References
    Article Figures
    Article Tables

 Article Access Statistics
    Viewed4019    
    Printed100    
    Emailed2    
    PDF Downloaded227    
    Comments [Add]    
    Cited by others 5    

Recommend this journal